Electromagnetic device for separation of fluid isotopes

ABSTRACT

This invention is related to an electromagnetic device for separation of the heavier isotopes from the lighter from a mixture of the two in fluid, particularly in gaseous state. This device consists of an essentially cylindrical enclosure with at least one of its circular walls covered with n coils, whose centerlines are spaced from each other by angles equal to 360*/n, and are fed from an n-phase source of AC, with each phase passed at least through a half-wave rectifier. Said coils create a radial magnetic field which rotates around the longitudinal axis of said cylindrical enclosure. The rotating magnetic field acting on positive ions of the gas pushes then toward the periphery of said enclosure. The ionization of said gas is brought about by means of a radioactive material emanating ionizing radiation, and/or a corona, or arc discharge between two electrodes, with the space between them passed by the gas. The ions of the lighter isotope, due to its smaller mass, have a larger velocity than have the ions of the heavier isotope. Therefore, the ions of lighter isotope are gathered at the periphery of said enclosure, from where they are directed through pipes, whereas the ions of the heavier isotope leave said enclosure near its center. Said difference in velocities of the ions of the different isotopes can also be achieved by means of a toroidal coil arranged at an entrance nozzle to said enclosure.

United States Patent [72] Inventor Henry Greber 225 West, 80 St... Apt. 8-D, New York, N.Y. 10024 [21 1 Appl. No. 738,542

[22] Filed June 20, 1968 [451 Patented July20,l971

[54] ELECTROMAGNETIC DEVICE FOR SEPARATION 0F FLUID ISOTOPES 1 Claim, 6 Drawing Figs.

521 0.5.0.... 250/419 [51] Int. Cl H0lj 39/34 [50] Field 01 Search 250/419 C,

[56] References Cited UNITED STATES PATENTS 2,724,056 11/1955 Slepian 250/419 3,004,158 10/1961 Steimel 250/419 Primary Examiner-James W. Lawrence Assistant ExaminerA. L. Birch ABSTRACT: This invention is related to an electromagnetic device for separation of the heavier isotopes from the lighter from a mixture of the two in fluid, particularly in gaseous state. This device consists of an essentially cylindrical enclosure with at least one of its circular walls covered with n coils, whose centerlines are spaced from each other by angles equal to 360ln, and are fed from an n-phase sourceof AC, with each phase passed at least through a half-wave rectifier. Said coils create a radial magnetic field which rotates around the longitudinal axis of said cylindrical enclosure. The rotating magnetic field acting on positive ions of the gas pushes then toward the periphery of said enclosure. The ionization of said gas is brought about by means of a radioactive material emanating ionizing radiation, and/or a corona, or are discharge between two electrodes, with the space between them passed by the gas. The ions of the lighter isotope, due to its smaller mass, have a larger velocity than have the ions of the heavier isotope. Therefore, the ions of lighter isotope are gathered at the periphery of said enclosure, from where they are directed through pipes, whereas the ions of the heavier isotope leave said enclosure near its center. Said difference in velocities of the ions of the different isotopes can also be achieved by means of a toroidal coil arranged at an entrance nozzle to said enclosure.

WENTEH JUL20 m FIG.2

FIG.4

FIG.6

INVENTOR.

ELECTROMAGNETIC DEVICE FOR SEPARATION OF FLUID ISOTOPES Chemical elements usually appear not as one isotope, but as a mixture of two or several isotopes. These have identical chemical but slightly different physical properties, due to their different masses. Because of these differences being slight, the separation of different isotopes from their mixture is difficult, and therefore expensive. The available methods for this purpose are:

1. Mass spectrometer.

2. Thermal Diffusion 3. Distillation.

4. Chemical exchange.

5 Gaseous Diffusion.

In the first method, the chemical element whose isotopes are to be separated, is evaporated and ionized. The ions are accelerated in an electric field and introduced into a magnetic field which causes their paths to be bent circularly. The path of the ions of the lighter isotope are bent into a circle of smaller radius than that of the heavier isotope. The two isotopes can be separated by putting appropriate collectors in proper locations of the enclosure in which the process takes place. This process has been tried in practice and has been found to be uneconomical. Also the other three methods,

thermal diffusion, distillation, and 'chemicalexchange, have been evaluated in the same way. Gaseous diffusion is the most practical, and therefore the most important method. It is based on that the molecules of the lighter isotope have a larger average velocity than have those of the heavier. A porous barrier, with pores so small that they permit the passage of single molecules only, let through predominantly the lighter isotope, so that the gas behind the barrier contains somewhat more of the lighter isotope than has the gas before the barrier. This enrichment has to be paid for by a considerable, energy consuming pressure drop of the gas between the two sides of the barri- This method has been applied for the separation of U from U The only compound of uranium that is a gas is uranium hexafluoride U -"F and U F To apply the gas diffusion method, yellow cake U 0, containing only 0.711 percent of U has to be converted into uranium hexafluoride, which is a solid subliming to gas when it is slightly heated. For this purpose, the uranium ore is dissolved in nitric acid for formation of uranyl nitrate. It is then evaporated and calcinated to U0 The UO is reduced to U0 which in reaction with an hydrous hydrofluoric acid is converted into UF, (green salt). This is fiuorinated with fluorine to produce UF The aim is to enrich this gas to 2 to 4 percent U to make it suitable as a fuel for nuclear reactors. This is done by the mentioned gaseous diffusion. Though it is the best available, it is not an easy method. One reason for this is that the velocity of a molecule is proportional to the square root of its molecular weight. The square root of the ratio /fi FJu -"F is 1.0043, only slightly different than one. Therefore for the required, though small enrichment a great many stages, that is passages through porous barriers are necessary. This accounts for the enormous energy requirements of gas diffusion plants.

It might appear that these could be avoided by the use of a centrifuge for separation of the two isotopes of the gas. A major advantage of the centrifuge method is that the separation depends only on the difference of the masses, not on their ratio, as it does in the preceding method. This leads to the further advantage that heavy and light element isotopes could be separated in the same centrifuge. Of course, for any such separation a mechanical centrifuge of extremely high speed would be necessary. Speed, however, is limited by the allowable stresses in the material used for manufacturing of the centrifuge. Speed is also limited by the bearing friction losses and by the friction losses in the gas itself as well as the friction losses of parts revolving at high velocities. The idea of using a centrifuge for isotope separation has been tried and abandoned, for the above-mentioncd reasons, which have led to enormous energy requirements at comparatively low outputs of these devices.

This invention is also based on a cen'trifugaV' force acting on the ionized gas molecules. Its central idea is that this force is not produced by rotation of the gas ions, but by rotation of the magnetic field acting on the gas. Obviously, rotation of a magnetic field causes no stress in mechanical components no bearing friction losses, no friction losses in the gas and on parts revolving at high velocity. This field, however, causes the same effect as that of mechanical rotation of the gas, that it it creates a radial force which acts differently on the different isotopes, because of their divers masses. Another, auxiliary means for the production of such force is the application of a circular magnetic field, produced by a toroidal coil around the constriction of a nozzle through which the gas enters into a container.

Consequently the purpose of this invention is to separate two or more isotopes of an element from their mixture, by means of ionizing this mixture and by applying to it a rotating magnetic field. Another purpose of this invention is to minimize the energy requirement for this separation, by applying the mentioned magnetic fields separately, or in combination. A further objective of this invention is to provide a device for isotope separation which has no moving parts. A still further purpose of this invention is to reduce the energy consumption required for this isotope separation through recombination of the ions. All these purposes are achieved by application of the mentioned magnetic fields on the gas ions. The enumerated and other connected with them advantages of this electromagnetic device for isotope separation will become apparent from this specification taken in conjunction with the accompanying drawing.

In this drawing,

FIG. 1 is a somewhat schematic front view of the electromagnetic device for isotope separation, and

FIG. 2 is a longitudinal cross-sectional view taken along line l-l";

FIG. 3 is a schematic wiring diagram showing a transformer whose secondaries are provided with half-wave rectifiers supplying the coil for production of the rotating magnetic field;

FIG. 4 is a schematic wiring diagram showing a transformer with a set of full-wave rectifiers feeding pairs of coils producing a rotating magnetic flux.

A longitudinal cross-sectional view of an electromagnetic device for isotope separation in which two toroidal coils and a nozzle are used, is shown in FIG. 5.

FIG. 6 depicts a cross-sectional view of a device for the same purpose in which two sets of coils for production of a rotating magnetic field are shown.

In detailed consideration of FIG. I of the drawing, it can be seen that the metallic nonferrous enclosure 2, carries three special coils 3, 4, 5, all being essentially cylindrical coils bent into concentric arcs. When one of the three coils carries its maximal current it produces a radial magnetic flux, each flux is represented by an arrow, labeled with the numerals 6, 7, 8. Enclosure 2 is surrounded with the eccentric scroll 9, which is provided with the outlet 10, and the merely indicated pedestal 75. The toroidal coil 11 is wound immediately on the inlet tube 12. Inside tube I2 is visible the ionizing mesh 13.

The same details, designated with the same respective numerals, appear in the cross-sectional view of FIG. 2. Here it can be seen that coil 3 consists of windings 14 which are wound in planes perpendicular to the inclined part of the wall of enclosure 2. The same can be said about windings 15 of coil 4. The potential source 16 feeds the ionizing electrodes 13, and 17. The toroidal coil 11 surrounds the entrance of tube 12 into housing 2. This coil (11) is a helically wound coil, with the helix bent to form a circle. The sources of potential feeding coils 3, 4, 5, and 11 are not shown for simplicity, but are sketched in the following schematic diagrams S, and 6. Outlet pipe I0 serves for the exit of the light isotope, and pipe 18 constitutes the exit of the heavy isotope. Pipe 18 contains the collecting electrode 19, which is connected by means of conductor 20, with collecting electrode 21, mounted in exit outlet 10. Conductor 22 connects both electrodes, 19 and 21 with the energy conversion device 23, which can be a motor, a heater, or any other device consuming electric energy. The same device 23, is connected, by means of conductor 24 to ground 25. Arrows 26 and 27 indicate the fluxes produced by coils 3 and 4 respectively, and arrows 28 and 29 show the velocities of the ions accelerated by the respective magnetic fluxes 27, and 26.

The wiring diagram shown in FlG. 3, represents the primary winding 30, of a three-phase, star-star connected transformer, whose secondary windings 31, 32, and 33 are each connected to the half-wave rectifiers 34, 35 and 36. The latter feed the coils 3, 4, 5, of FIGS. 1 and 2. It can be seen that coil 4 carries its maximal current after a time l/3f, wherefis the frequency of the current, after coil 3 has carried its maximal current. A similar time delay between the occurrences of the maximal currents exists between coils 4 and 5, and also between and 3. The current flowing in conductor 37 is DC whose value, if

the ripples are neglected for simplicity, is constant. Therefore, the toroidal coil 11 is inserted into this conductor.

A similar scheme, but with the application of full-wave rectification is diagramed in FlG. 4. The primary winding of the shown transformer is designated with 38. The secondary windings 39, 40, and 41 are connected to the rectifiers 42, 43, and 44. The terminal of winding 39 is also connected to the pair of coils 45, 46. Similarly, the terminal of winding 40 is connected to the coil pair 47 and 48, whereas the terminal of winding 41 is linked to the pair of coils 49 and 50. The terminals of coils 45, 47, and 49 are connected to the set of rectifiers 51, 52, and 53. It can be seen that coil 11 is inserted into the run of conductor 54, which connects the two rectifier sets 42, 43, 44 and 5], 52, 53. For reasons given in the preceding, the maximal currents flowing in the coils pairs, 45,46, and 47, 48, and 49, 50, are displaced in time against each other by one third of one period. While these currents flow always in the same directions, their values fluctuate from zero to a maximum and back to zero, the current in conductor 54 is a continuous, nonfluctuating current, if the relatively small ripples of the DC are ignored for'simplicity. Therefore, toroidal coil 11 is inserted into the run of conductor 54.

In F IG. 5 is shown a longitudinal cross-sectional view of a device similar'to that drawn in FIG. 1, except that it has two toroidal coils 55 and 56, mounted on opposite sides of enclosure 57. The inlet pipe 58, contains the ionizing electrodes 59, 60, fed from a voltage source 61. At the entrance to enclosure 57, pipe 58 has a nozzle with constriction 76, at which the ions achieve their maximal velocity. Pipe 62 constitutes the exit of the heavy isotope. The light isotope leaves enclosure 57 through exit 77.

A similar longitudinal cross-sectional view of a device provided with two sets of coils producing a rotating magnetic field is shown in FIG. 6. The inlet pipe 63, contains the ionizing electrodes 64 and 65, fed from the potential source 66, enclosure 67, has inclined walls carrying the opposite coil pairs 68, 69, and 70, 71. These are connected in a manner shown in the diagram of FIG. 4. The scroll 72, has an exit 73, serving for the light isotope. Pipe 74, serves for the exit of the heavy isotope.

The mode of operation of this electromagnetic device can be best explained on basis of FIGS. 1 and 2. The key factor in this operation is the radial magnetic flux produced by the coils 3, 4, 5. Let coil 3 carry the maximal current at a given moment, and produce the radial flux 6. After one third of a period, coil 4 will be carrying its maximal current and the radial magnetic flux will take on the position indicated by the arrow 7. After two thirds of a period the position of the rotating magnetic flux will be that indicated with arrow 8. This rotating magnetic flux acts on the fluid, in particularity on the gas ions accumulated in enclosure 2. All molecules of the gas are ionized. This is achieved through their passage through the gap between ionizing electrodes 13, 17. A gas discharge, specifically a corona discharge or an arc discharge between these electrodes, is capable of ionizing all gas molecules passing through this gap. lf it is assumed that the first electrode (l3), encountered by the gas is negative, and the second (17) is positive, then the latter will attract and neutralize all the electrons freed from the neutral gas molecules at their ionization on the first electrode (13). Electrode 13 is connected to ground 25. So, in consequence, only the heavy positive ions willremain in the gas. These ions fill enclosure 2, and are acted upon by the rotating magnetic field, just described. Due to this rotating field a radial force acts on the ions. This force is completely equivalent to a centrifugal force which would act on these ions, were they set into mechanical rotation. The mentioned radial magnetic force acting on the ions depends only on their charge, on the magnitude of the magnetic field and on the speed of its rotation, that is on the frequency of the AC current, but does not depend on their masses. The ions of the lighter isotope, however, acted upon by the same radial force as the ones of the heavier isotope, develop a greater velocity, because of their smaller mass. In consequence, ions of the lighter isotope gather at the periphery of the enclosure 2, while ions of the heavier isotope remain nearer to the centerline of said enclosure 2. As a result, gas taken from the periphery of enclosure 2 is enriched with the lighter isotope, while the gas taken from the center of enclosure 2, is enriched with the heavier isotope. Since the only rotating part" in this device is the magnetic flux, its energy consumption is naturally low. To lower it still more, and regain a considerable part of the energy invested into ionization of the gas, the positive ions, of both isotopes are caught on mesh-shaped electrodes, 19, and 21 and neutralized by returning to them the electrons taken away from them at the process of ionization. This returning of electrons gives back almost all energy spent for ionization, and can be utilized in an electric energy consuming device 23. It is obvious, that the regained energy can be used for ionization of further oncoming parts of the gas to be isotope separated.

As mentioned, this invention comprises also a second mode of operation, that consists in the creation of a peripheral magnetic flux, whose lines of force are circles around the axis of the device. Such flux can be easily produced by means ofa toroidal coil, that is a coil in form of a helix, which is then bent into a circular shape. A positive ion carried by the gas stream and reaching the position right under said toroidal coil is acted upon by a radial force. This electromagnetic force is fully equivalent to a centrifugal force which would act on said ion, were it rotated in a centrifuge. The electromagnetic force on the ion is the same regardless whether it belongs to the lighter or to the heavier isotope. However, the same force acting on a ion of the lighter isotope develops a larger velocity, because the ion is lighter than that of the heavier isotope. As a result, ions of the lighter isotope gather at the periphery, and ions of the heavier isotope gather at the center of enclosure 2. It can be seen that the first mode of operation has the advantage over the second that it is applicable to large parts of the gas, in fact to the entire gas in the enclosure. By the second mode of operation only the gas near the plane of interpenetration of the inlet tube with the enclosure can be influenced. Since in the second mode of operation the radial force depends on the velocity of the positive gas ions, these can be accelerated by mounting a nozzle at the entrance to the enclosure. This is shown in FIG. 5.

As stated a major objective of this invention is the reduction of the energy consumption required for isotope separation. A further step in this direction is the replacement of ionization by a corona or are discharge, by ionization of radioactive materials deposited on, or implanted in one of the ionizing electrodes.

As mentioned, this invention can be used for gas as well as for electrolytes. It can be used for gas compressors or blowers and also for pumps with no moving parts. The outputs of these devices could be simply controlled by means of changing the frequency and/or voltage of exciting windings producing the magnetic fluxes. Many other modifications, changes and variations of this device, by addition or subtraction, or substitution of parts with equivalents, and by adapting this invention to different applications in which it can be used, can be made without departure from its essence, all within its scope, as defined with the following claims.

lclaim:

1. An electromagnetic device for separation of fluid, particularly of gaseous isotopes, comprising:

a. a cylindrical enclosure having an entrance end through which said gaseous isotopes are supplied;

b. an ionization means within said enclosure adjacent said entrance end for ionizing the gaseous isotopes supplied;

04 a number, N, of magnetic coils disposed about the periphery of said cylindrical enclosure, the axial centerlines of said coils being directed toward the center of said enclosure and spaced-apart from each other by angles equal to 360/N;

d. a toroidal coil disposed about the periphery of said cylindrical enclosure; 7

e. a power supply means, including an N-phasc AC voltage source and a rectifier means, for energizing said magnetic and toroidal coils;

f. a first ion collector means disposed adjacent the periphery of said cylindrical enclosure; and

g. a second ion collector means disposed adjacent the center of said cylindrical enclosure; whereby said coils create a radial magnetic field which rotates around the longitudinal axis of said cylindrical enclosure causing the lighter isotope to be collected by said first ion collector and the heavier isotopes to be collected by said second ion collector. 

1. An electromagnetic device for separation of fluid, particularly of gaseous isotopes, comprising: a. a cylindrical enclosure having an entrance end through which said gaseous isotopes are supplied; b. an ionization means within said enclosure adjacent said entrance end for ionizing the gaseous isotopes supplied; c. a number, N, of magnetic coils disposed about the periphery of said cylindrical enclosure, the axial centerlines of said coils being directed toward the center of said enclosure and spaced-apart from each other bY angles equal to 360*/N; d. a toroidal coil disposed about the periphery of said cylindrical enclosure; e. a power supply means, including an N-phase AC voltage source and a rectifier means, for energizing said magnetic and toroidal coils; f. a first ion collector means disposed adjacent the periphery of said cylindrical enclosure; and g. a second ion collector means disposed adjacent the center of said cylindrical enclosure; whereby said coils create a radial magnetic field which rotates around the longitudinal axis of said cylindrical enclosure causing the lighter isotope to be collected by said first ion collector and the heavier isotopes to be collected by said second ion collector. 